It will be the first meeting between Obama and Erdogan since the failed attempted coup in Turkish last month.
Teenage pupils from Eton College were welcomed into the Kremlin for a two-hour audience with Vladimir Putin.
The 11 students - some of whom were wearing official Eton school ties - were pictured shaking hands with Putin and sitting around a table with him in Moscow last week.
While UK Prime Minister Theresa May will not meet the Russian president until an worldwide summit next week, 11 schoolboys were able to chat with him and take photos. They later jokingly posed for pictures in the Kremlin.
The school, which was founded in 1440 and has educated 19 British prime ministers, said in a statement: "This was a private visit by a small group of boys organised entirely at their own initiative and independently of the college". "I would assume it was so the school didn't find out because I don't think they would be happy".
"I know the boys through friends, who showed me the pictures on social media".
The details of how the Eton College students managed to pull off this coup remains a mystery.
The boys didn't appear to have signed any confidentiality agreements barring them from discussing the meeting - as they have been gushing about it since on social media. "We are ready, although the final decision has not been made yet", he added.
Ushakov also said that a previously agreed trilateral meeting of leaders from Russia, Germany and France, who were poised to discuss Ukraine's crisis, will not take place.
Apart from the G20 summit in China, another likely occasion for a meeting between the two presidents this year is the APEC summit to be held on November 18-19 in Peru.